Rooftop units are assembled onto the flat roofs of structures such as supermarkets, office buildings and other commercial structures. These units are factory assembled and tested, needing only to be hoisted to the roof at the site for installation. A rooftop unit may be used for heating, cooling or both.
Chillers, or chilled water units, are cost-effective systems that utilize both water and refrigerant. Chillers remove heat from the water, which is then circulated through other components in the system. Water is an excellent secondary refrigerant because it is readily available, inexpensive, non-toxic and substantially non-corrosive. It also has a favorable specific heat value. Other secondary refrigerants can also be used, depending upon the application. These include calcium chloride or sodium chloride brines, methanol, propylene glycols, ethylene and glycerin. Chillers are frequently used for commercial air conditioning and industrial process cooling as well as for low temperature refrigeration. While there are various types of chillers, which may include many different components, a chiller typically includes a compressor, a motor and a control center, which may be in the form of a microprocessor control. A compression chiller will include, in addition to the above equipment, a condenser, an evaporator and a metering device.
Various literature is available discussing the benefits of remote monitoring of HVAC systems. One such patent to Sandlemen et al., U.S. Pat. No. 6,535,123 B2 issued Mar. 18, 2003, discusses the remote monitoring of electric and/or mechanical equipment such as HVAC equipment. It discloses using a sensor to monitor the state of at least one parameter of the equipment and communicating a message indicative of the equipment state to a locally connected interface unit which is in communication with a computer server. A user can remotely access the computer server through a user interface to configure outgoing message routing instructions. When a sensor detects an exception condition, the interface unit forwards a message indicative of the exception condition to the server, which forwards it to at least one predetermined user-defined remote communication device based on the incoming exception message. An “exception condition” occurs whenever the equipment operates outside of its preferred parameters, and an error message is transmitted to a recipient indicative of the condition unless the feature is disabled.
Such systems suffer from a few inadequacies. First, it fails to recognize that chillers, and frequently rooftop units, already include sensors that monitor operational parameters and transmit this information to the control center. Therefore, it would be beneficial if the information available at the on-site control centers could be utilized to provide valuable information indicative of system operation to a remotely located individual, rather than rerouting the information transmitted from the sensors to such equipment as discussed in U.S. Pat. No. 6,535,123 B2. The control centers provided with chillers differ for each chiller manufacturer, and so accessing the information received by the control centers can prove to be more difficult than rerouting information transmitted from the sensors to such equipment or providing new sensors.
Systems such as discussed in U.S. Pat. No. 6,535,123 B2 provide for initiation of two-way communication between the user and the remotely located site, as discussed in the patent. This two-way communication, particularly when set up to operate over the Internet, is subject to mischief by hackers who can cause false exception messages necessitating unnecessary technician service calls, or worse, shutting down the equipment.
Current methods of monitoring the operation of chillers or rooftop units of air conditioning systems currently do not provide the capability to both remotely diagnose an existing problem or anticipate the occurrence of a problem that could result in shut down or improper operation of equipment. One of the results of the current methods is that service technicians are called to the site of the chiller or rooftop units when repairs are not required. Alternatively, the service technicians may be dispatched to a repair site and may not have the correct parts or equipment to repair the malfunctioning unit. In another scenario, the technicians are dispatched to repair a malfunctioning unit on an emergency basis, frequently at inconvenient times, after a failure has occurred. For the technician, this means reduced productivity. More importantly, it can result in reduced performance to other customers, as the technician(s) is required to respond to reports of malfunctioning units on an emergency basis.
A system of remotely monitoring a chiller system that utilizes information from the control center of the unit would be beneficial. While the system of monitoring is remote and provides important information about the operation of the system, such a system should not, for security reasons, allow a remote user to gain access to the information in the system from his remote location.